What is making my file so heavy?
Your file is 380 MB heavy.  One part is that you have high poly objects with 2 UV maps for each object. That's about 150 MB. You can delete the UV maps to save space. There are also Custom Split Normals Data, about 20 MB. Then, it's still 215 MB big, but I'm not sure why Blender still needs that many bytes...?
Why it doesn't render
As already mentioned you have a few high poly objects in your scene. Each of these objects has something like 257,000 vertices, 607,000 edges, 350,000 faces - and they have a Subdivision Surface modifier, Viewport level: 0, Render level: 1. That's the problem.
If you render this, the modifier kicks in and adds some geometry... 1.2 million vertices, 2.4 million edges, 1.2 million faces for one object. This is multiplied by the number of objects and ... good night ;-)
Solution: Remove the modifiers and it will render fine.
To decrease the render time you can use the default 128 samples, tick [X] Adaptive Sampling, and use the denoiser in the compositor.
Also, these objects in the background can be rather low-poly. 5k or 10k vertices with a bump/normal map should do the trick. No need for 257k vertices.

128 samples, AA, denoiser node, 20 minutes render time (CPU), 1.5GB mem peak